1. Field of the Invention
This invention relates generally to a method and apparatus for speech recognition and, more particularly, to a speech recognition system in which input speech signals are matched with already registered signals to obtain speech recognition.
2. Description of the Background
There have been proposed speech recognition systems having countermeasures against fluctuations in the utterance speed of speech that use the so-called dynamic programming (DP) processing. Such a system is disclosed, for example, in published Japanese patent application No. 96104/1975. According to such known speech recognition apparatus using the dynamic programming matching processing, speech recognition can be carried out by matching input speech signals against stored templates without problems of utterance speed fluctuation and differences in word lengths, because the time dimension of the input is optimally warped, that is, time-normalization is performed.
In such speech recognition apparatus using dynamic programming matching processing to accomplish time-normalization, when the number of words to be recognized is increased, there is the further problem that the calculation time and memory capacity necessary for dynamic matching programming processing are inevitably and unfortunately increased.